Non-Parabolic Solar Concentration to an Area of Controlled Flux Density Conversion System

ABSTRACT

A solar conversion system with a solar collector that is shaped to focus reflected sunlight along an area with a substantially constant flux density. The area shape can be resemble a rectangular, square, circular, or other shape. Included with the system is a solar conversion module having a photovoltaic cell that is alignable with the area. The cell converts the focused reflected sunlight into electrical energy when aligned with the area.

RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalApplication Ser. No. 61/249,202, filed Oct. 6, 2009, and U.S.Non-Provisional application Ser. No. 12/899,337, filed Oct. 6, 2010, thefull disclosure of which is hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates in general to a solar conversion systemthat concentrates solar energy non-parabolically and converts theconcentrated energy into electrical energy. More specifically, thepresent disclosure includes a solar conversion system having anon-parabolic solar collector that concentrates reflected solar energyinto a focal area of controlled flux density.

2. Description of Prior Art

FIG. 1A illustrates a prior art view of a solar conversion system 20shown in a side perspective view. The solar conversion system 20includes a parabolic dish 22 having a reflective surface 24 on itsconcave side that reflects sun rays 26 to form reflected rays 28. Thedish 22 concentrates the reflected rays 28 towards a focal point 30offset a distance from the dish 22. A receiver module 32 is disposed inthe path of the reflected rays 28 with its front surface positionedbetween the focal point 30 and the dish 22. FIG. 1B shows a side of thereceiver module 32 facing the dish 22 and illustrates the receivermodule 32 with a module surface receiving the reflected rays 28. Themodule 32 includes a mounting base 34 having a photovoltaic cell 36 ismounted thereon. The concentrated reflected rays 28 form a circularimage 38 on the photovoltaic cell 36. The flux density of the image 38on the cell 36, for example, may be a thousand times the flux densityreceived by the dish 22. The high intensity light flux may damage orshorten the life of the photovoltaic cell 36 by direct exposure or heatbuildup in the module 32. The heating of the module 32 and cell 36 isexacerbated by disposing the module 32 in the direct sunlight.

FIG. 2A illustrates one known method to reduce the thermal energyapplied to the module 32A. Shown in a side view is a solar conversionsystem 20A having a parabolic leaf 23 with a reflective surface 24A onits concave side. Sun rays 26 reflect from the parabolic leaf 23 asreflected rays 28 that converge to a focal point 30A below the midpointof the leaf 23. This is unlike the dish 22 whose focal point 30 isbisected by a line disposed substantially normal to the midpoint of thedish 22. Lowering the focal point 30A below the midpoint of the leaf 23positions the corresponding receiver module 32A on the convex side of anadjacent forward leaf 23. As shown in the upward looking plan view ofFIG. 2B, the concentrated reflected rays 28 from the leaf 23 create animage 38A having inconsistent flux density onto a photovoltaic cell 36A.The uneven flux limits the total energy that may be converted by themodule 32A due to the low density flux portions of the image 38A. Theimage 38A in FIG. 2B illustrates the leaf 23 of FIG. 2A unevenlyconcentrating rays to create high density flux areas on the photovoltaiccell 36A that may exceed operational limits of the cell 36A and damagethose areas.

SUMMARY OF THE INVENTION

Disclosed herein is a solar energy conversion system to convert solarlight energy into electrical energy. In one example, the conversionsystem includes a first solar collector having a reflective frontsurface contoured so that when positioned to receive solar light energyfrom the sun, the solar light energy contacts the reflective surface, isreflected from the collector outwardly from the reflective surface, andis concentrated in a planar portion of a plane having substantiallyconstant flux density throughout the planar portion to thereby define aplanar focal area, a photovoltaic cell having at least a portion of asurface coincident with the planar focal area to receive theconcentrated light energy thereon, and a resistive load in electricalcommunication with the photovoltaic cell so that the concentrated lightenergy received by the photovoltaic cell is thereby converted toelectrical energy and communicated to the resistive load. The planarfocal area can be formed so that it resembles shapes such as, but notlimited to, a rectangle, a square, a circle, or an ellipse. In oneexample, the ratio of planar focal area to photovoltaic cell surfacearea can range from about 1:2 to about 2:3. The collector can beprofiled so discrete amounts of solar light energy reflect fromlocations on the reflective surface to define paths from the reflectivesurface to corresponding locations on the focal area. In one example ofthe system the paths defined by the reflected solar energy do notintersect. Other embodiments may include paths of reflected solar energythat intersect in any manner. The system may further include a secondsolar collector having a front surface and a rear surface positioned toface the reflective front surface of the first solar collector, a shadedarea adjacent the second solar collector rear surface, and wherein thephotovoltaic cell is connected to the rear surface of the second solarcollector and positioned within the shaded area to receive solar lightenergy when reflected from the reflective front surface of the firstsolar collector. A heat transfer system can optionally be included thatis in thermal communication with the photovoltaic cell. A multiplicityof additional collectors can be added along with correspondingphotovoltaic cells, wherein the collectors are arranged in rows to forman array of collectors.

The present disclosure includes a method of converting solar energy toelectricity. In one example the method includes providing a collectorcomprising a reflective side profiled so that when light rays reflectfrom the reflective side, they converge to a focal area having asubstantially uniform flux density, providing a solar conversion cellhaving a surface that coincides in space with the focal area, orientingthe collector so that the reflective side is in the path of rays fromthe sun that contact and reflect from the reflective side of thecollector and converge onto the surface of the solar conversion cellwith substantially uniform flux density that is converted to electricityin the solar conversion cell, and directing the electricity converted bythe solar conversion cell to a resistive load. The focal area of themethod can be approximately shaped as desired, including but not limitedto a rectangle, a square, a circle, a polygon, or an ellipse. Thecollector can be positioned to receive maximum light intensity from therays contacting the collector. Alternatively, the collector can reflectsun rays to converge onto the surface of the solar conversion cell in acontrolled, non-uniform flux. Optionally, the method can involveorientating the collector in a position to receive maximum lightintensity from the rays contacting the collector as the sun changes itsrelative position to the collector. A second collector can be includedin the present method, where the second collector has a reflective side,and the method includes placing the second collector in substantiallythe same orientation and in front of the collector, positioning thesecond collector so that its side opposite its reflective side isadjacent the solar conversion module, and mounting the solar conversioncell onto the second collector. The solar conversion cell can be placedin an area shaded by the second collector. In an alternative embodiment,the method can include repeating the steps of providing the collectorand conversion cell so that multiple collectors with correspondingmultiple solar conversion cells are provided. The reflective surface canbe profiled so that when it is positioned in the path of light from thesun, discrete amounts of solar light energy reflect from locations onthe reflective surface and define paths from the reflective surface tocorresponding locations on the focal area and wherein the paths do notintersect. Other embodiments may include paths of reflected solar energythat intersect in any manner. Optionally, the size of the focal area canbe a percentage of the size of the solar conversion cell.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the features and benefits of the present invention having beenstated, others will become apparent as the description proceeds whentaken in conjunction with the accompanying drawings, in which:

FIG. 1A is a side perspective view of a prior art solar conversionsystem.

FIG. 1B is a plan view of an image projected onto a module by the solarconversion system of FIG. 1A.

FIG. 2A is a side view of a prior art solar conversion system.

FIG. 2B is a plan view of an image projected onto a module by the solarconversion system of FIG. 2A.

FIG. 3A is a side perspective view of an example of a solar collector inaccordance with the present disclosure.

FIG. 3B is a sectional view of the solar collector of FIG. 3A takenalong section lines 3B-3B.

FIG. 3C is a sectional view of the solar collector of FIG. 3A takenalong section lines 3C-3C.

FIG. 4A is a side perspective view of an example of a focused beamhaving a substantially uniform flux density and formed using thecollector of FIGS. 3A-3C.

FIG. 4B is an enlarged perspective view of the focused beam of FIG. 4A.

FIG. 5 is a side view an embodiment of a solar conversion system inaccordance with the present disclosure.

FIG. 6 is an overhead plan view of the collector and focused beam ofFIG. 4A.

FIG. 7 is an overhead plan view of an example of a solar conversionmodule in accordance with the present disclosure.

FIG. 8 is an overhead plan view of a focused beam imaged on the solarconversion module of FIG. 7.

FIGS. 9A and 9B are side views of an example of a solar conversionmodule disposed in spaces that are shaded by a solar collector.

FIG. 10 is a side view of an example of a collector and a correspondingfocal beam in accordance with the present disclosure alongside aparabolic collector and its focal point.

FIGS. 11A and 11B are perspective views of flux densities for the focalbeam and focal point of FIG. 10.

FIG. 12 is a schematic example of a solar conversion system inaccordance with the present disclosure.

FIG. 13 is a perspective view of a solar collector in accordance withthe present disclosure.

FIG. 13A is an overhead view of the solar collector of FIG. 13.

FIG. 13B is a bottom plan view of the solar collector of FIG. 13.

FIG. 14A is a front elevational view of a solar collector in accordancewith the present disclosure.

FIG. 14B is a rear elevational view of the solar collector of FIG. 14A.

FIG. 15A is a downward plan view of a solar collector in accordance withthe present disclosure.

FIG. 15B is an upward looking view of the solar collector of FIG. 15A.

FIG. 16 is a perspective view of an example of a solar collector arrayset in frames, in accordance with the present disclosure.

It will be understood the improvement described herein is not limited tothe embodiments provided. On the contrary, the present disclosure isintended to cover all alternatives, modifications, and equivalents, asmay be included within the spirit and scope of the improvement asdefined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theillustrated embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art.Like numbers refer to like elements throughout. For the convenience inreferring to the accompanying figures, directional terms are used forreference and illustration only. For example, the directional terms suchas “upper”, “lower”, “above”, “below”, and the like are being used toillustrate a relational location.

It is to be understood that the invention is not limited to the exactdetails of construction, operation, exact materials, or embodimentsshown and described, as modifications and equivalents will be apparentto one skilled in the art. In the drawings and specification, there havebeen disclosed illustrative embodiments of the invention and, althoughspecific terms are employed, they are used in a generic and descriptivesense only and not for the purpose of limitation.

FIG. 3A illustrates a side perspective view of an example of a collector42 in accordance with the present disclosure. A reference X-Y-ZCartesian coordinate axis is included with FIG. 3A, wherein the Z axisrepresents a spatial vertical reference. The collector 42 of FIG. 3A isa thin member having an elongate length and tilted so that one of theends in the elongate direction is elevated on the Z axis with respect tothe other. The collector 42 is profiled along its length and width. Thecollector 42 can include aluminum 5052 and be formed by a stampingprocess. The concave surface can be polished to create a reflectivesurface having up to about an 85% reflectivity. Optionally the concavesurface can be coated to make it reflective. Other materials for use inmaking example collectors 42 include glass, composites, and moldedplastic materials. Referring now to FIG. 3B, a sectional view of thecollector 42 is illustrated taken along the width of the collector 42 atsection lines 3B-3B. Illustrated in FIG. 3B, the collector 42 has acurved profile between its lateral elongate sides such that itsrespective lateral edges are at an elevation different from its midportion. A reference width axis A_(W) is included in FIG. 3B orientedparallel to the Z axis, and perpendicular to the Y axis. In the exampleof FIG. 3B the collector 42 width is substantially symmetric about itsaxis A_(W).

FIG. 3C illustrates an example of the collector 42 in a side sectionalview along its length at sectional lines 3C-3C. Similar to the profilealong the width of the collector 42, the profile along the length of thecollector 42 is generally concave. A reference length axis A_(L) isshown on the collector 42 at about the midpoint of its length. The axisA_(L) is oblique to both the Z and X axes and normal to a line extendingbetween the elongate ends of the collector 42. The length of thecollector 42 of FIG. 3C is not symmetric about axis A_(L). Moreover, thelengthwise section illustrated in FIG. 3C is not parabolic. The profiledlength and width form a concave side of the collector 42 on which areflective surface 43 is disposed. For the purposes of discussionherein, depth in the collector 42 is the distance from the surface 43 toa line (not shown) extending from opposite ends of the collector 42 andparallel to one of axes A_(L) or A_(W).

FIG. 4A illustrates an example collector 42 having its reflectivesurface 43 oriented to receive solar light energy from sun, representedherein as sun rays 44 that reflect away as reflected rays 46. Thecollector 42 of FIG. 4A is configured so that the reflected rays 46converge and focus on a planar area to form a rectangular image 52 witha controlled flux density. In one example, a controlled flux densitymeans that a desired image flux density can be obtained by configuringthe collector 42 to create an image 52 with a particular flux density.Particular flux densities include those having a set total value, rangesof values across the image 52, a maximum/minimum value on the image 52,as well as a distribution or variance of values of flux density on theimage 52. An image 52 having a substantially constant flux density alongits area is an example of a controlled flux density. The planar area inwhich the reflected rays 46 converge may be referred to herein as afocal area. Alternatively, both the collector 42 and the image 52 cantake on any recognizable shape, such as a square, polygon, circle,ellipse, diamond, triangle, and the like, or the collector 42 and/orimage 52 can be a combination of recognizable shapes as well as anunrecognizable non-uniform shape. Referring now to FIG. 4B, an enlargeddepiction is provided of how the reflected rays 46 focus along an areacoincident with a plane 53.

FIG. 5 illustrates in a side elevational view an example of a solarconversion system 40 in accordance with the present disclosure. Thesystem 40 includes a collector 42 with a reflective surface 43; sun rays44 reflect from the reflective surface 43 to create reflected rays 46.As explained above, the collector 42 profile focuses the reflected rays46 into a focal area to create an image 52. The system 40 of FIG. 5further includes a receiver module 48 attached to, or in close proximityto, a forward collector 45. The module 48 is oriented so the image 52,formed by the converging reflected rays 46, is located on a surface ofthe module 48 facing the reflective surface 43. The forward collector 45may be substantially the same as the collector 42, and is illustratedpositioned on the concave side of the collector 42. The module 48 ismounted on, or in close proximity to, the convex side of the collector45. The system 40 may optionally include an additional multiplicity ofcollectors 42, 45 (not shown) and corresponding modules 48.

In one example of forming a collector 42, desired parameters for animage are established, and then dimensions and a configuration for acollector are determined that form an image based on the establishedparameters. Example parameters for the image 52 include a substantiallyuniform flux density within the focal area, dimensions of the image 52,a maximum angle of incidence between each reflected ray 46 and the plane53, and a flux magnitude of the image 52. The dimensions of the image 52and its flux magnitude can be specific to an application or dictated byoperational constraints, such as the type of conversion cell on whichthe image 52 is projected. In one example, as noted in more detailbelow, the dimensions of the image 52 are a percentage of the total areaof a corresponding solar conversion cell. Additional constraintsaffecting the design of the collector 42 include: (1) the module 48position; (2) establishing a maximum height of the collector; and (3) areflectivity value of the reflective surface. In an embodiment, themodule 48 is positioned at a fully shaded location on the back side ofan adjacent collector forward of the collector 42.

The dimensions of the collector 42 can be calculated based on theestablished values for the total flux of the image 52, the dimensions ofthe image 52, and the reflectivity of the reflective surface 43. Theimage 52 is partitioned into discrete areas of known dimensions and allpossible reflected rays are identified (within the maximum angle ofincidence) that can form each discrete area. Each ray identifiedreflects from a corresponding discrete area (element) on collector 42,where the corresponding element represents a possible location for aportion of the reflective surface 43. Thus, in one embodiment, overallarea of the collector 42 as seen by the sun can be based on a desiredsolar power concentration ratio from the collector 42 to the image 52and dimensions of the image 52. The length to width aspect ratio of thecollector 42 can be any one of many values and may be dependent on aparticular application or designer preference. The relative location ofthe collector 42 to the receiver module 48 can be set by the designerbased on the spatial constraints described above. Then both the surfacearea of the image 52 and of the collector 42 are each partitioned intodiscrete areas. The mid-point of each discrete area on the collector 42is mapped to a corresponding discrete area on the image 52. In oneexample, mapping includes spatially identifying the path of a reflectedray 46 that intersects the corresponding mid-points on the collector 42and the image 52. The XY coordinates of the mid-points of each discretearea on the collector 42 are known and the XYZ coordinates of themid-points of each discrete area on the image 52 are also known. Bymapping between corresponding mid-points on the collector 42 and image52, each discrete area of the collector 42 can be set at an angle todirect reflected rays 46 along the mapped path. Thus the angle andresulting Z value of each collector element can then be computed usingvector algebra.

FIG. 6 schematically depicts an example of how reflected rays 46 travelfrom the collector 42 on their way to forming the image 52. In thisexample, the collector 42 is illustrated in an overhead plan viewsimulating its orientation with respect to the sun. As shown, thecollector 42 is angled to horizontal, thus its apparent length (distancealong the X-axis) will be less than its actual length. In FIG. 6, theapparent length is illustrated using solid lines; the difference betweenapparent length and actual length L is represented by a dashed line. Thecollector 42 is partitioned into elements represented in matrix form as42 _(1, 1)-42 _(Xn, Yn). Although illustrated as having substantiallythe same length in the X direction, these elements 42 _(1, 1)-42_(Xn, Yn) may have different actual lengths due to how the collector 42is angled with respect to horizontal. The beam is also partitioned,shown having elements 52 _(1, 1)-52 _(Xn, Yn). Reflected rays 46 arefurther illustrated to represent reflected solar energy from eachelement of the collector 42 to the corresponding element of the image52. For example, reflective beam 46 from collector element 42 _(1, 1)passes to element 52 _(1, 1) and forms that portion of the image 52.Similarly, reflective beam 46 from element 42 _(Xn, 1) passes to element52 _(Xn, 1), reflective beam 46 from element 42 _(1, Yn) passes toelement 52 _(1, Yn), and so on. Although collector elements 42_(1, 1)-42 _(Xn, Yn) may vary in actual area, the flux produced by eachelement 42 _(1, 1)-42 _(Xn, Yn) can be substantially the same. Sinceeach element 42 _(1, 1)-42 _(Xn, Yn) can create the same amount of flux,the flux density across the image 52 can be made substantially uniform.

FIG. 7 illustrates an overhead plan view of an example embodiment of areceiver module 48. As shown, the receiver module includes a base 49illustrated as a largely rectangular member having a receiver assembly50 mounted onto the base 49. The receiver assembly 50 includes arectangular shaped conversion cell 54 disposed roughly in the midsection of the receiver assembly 50 and on a module substrate 56. In oneexample, the conversion cell 54 is a photovoltaic cell for convertinglight energy into electrical energy. A diode 58 is shown included withthe receiver assembly 50 that is electrically connected with theconversion cell 54 and leads 60, 62 on which wires (not shown) or otherelectrically conducting members can be attached for delivering currentfrom the conversion cell 54 for use or storage.

The receiver assembly 50 is illustrated in an overhead plan view in FIG.8 with an example of the image 52 positioned on the conversion cell 54.For the purposes of discussion herein, in an example, the image 52 ispositioned on the cell 54 when the plane 53 (FIG. 4B) in which it isfocused coincides with the upper surface of the conversion cell 54.Optionally, the plane 53 where the image 52 is focused could be justabove or just below the upper surface of the conversion cell 54. In thisexample, the image 52 is largely rectangular with an area less than thearea of the conversion cell 54. In one example of use, the collector 42(FIG. 6) is profiled to form the image 52 at a set percentage of theconversion cell 54 where example percentages include 50%, 55%, 60%, 64%,65%, 70%, 75%, and 95%. An advantage of an image 52 having an area lessthan the area of the conversion cell 54 is the image 52 can bemisaligned (e.g. not centered on the cell 54) and yet still project itsfull area onto the conversion cell 54. Additionally, in an embodiment,the system described herein reflects sunlight directly to a conversioncell without the reflected light encountering a cover, lens or asecondary reflector. A secondary reflector can reduce efficiency by upto 10% from the design disclosed herein.

FIG. 9A illustrates in a side view a module 48 on the convex side of aforward collector 45. In this example, the module 48 receives reflectedrays 46 while in a shaded area 64 shielded by the forward collector 45from direct sunlight. The shaded area 64 is bounded on one side by thecollector 45 and on its other side by line 66 shown extendingsubstantially vertical and depending downward from the collector 45upper edge 68. Optionally, as shown in FIG. 9B, the receiver 48A couldbe disposed at multiple positions along the convex side of the collector45 within the shaded area 64. The position of the module 48A willdictate direction and orientation of the reflected rays 46A contactingthe module 48A.

FIG. 10 illustrates in a side view a parabolic-type collector 13positioned adjacent a collector 42 formed in accordance with the presentdisclosure. Also shown is an example of how the reflected rays 18Aconverge at the focal point 20A of the parabolic reflector 13; and howthe reflected rays 46 converge to form the constant flux density image52. FIGS. 11A and 11B provides an illustration of how the flux densityof reflected light differs between the parabolic type collector 13 andcollector 42 as disclosed herein. A plot representing the flux densityof the image 52 of FIG. 10 is provided in a perspective view in FIG.11A. The units of flux density are flux/unit area, thus representingflux over the surface area of the image 52. The flux density of theimage 52 as shown remains substantially the same along its entire area.As discussed above, concentrated solar collectors employing parabolicreflectors typically have their conversion cell between the collectorand focal point. FIG. 11B illustrates a plot representing example fluxdensity values of an image formed by reflected rays 18A from theparabolic-shaped collector 13 and projected onto a solar cell. The fluxdensity values illustrated in FIG. 11B are not substantially the sameacross its area, but instead slope upward from the periphery having amaximum towards the mid-portion of the image. This can create highenergy areas on the conversion cell that may damage the cell and mayrequire reducing the overall concentration ratio of a collector so thatthe maximum flux on any part of a cell does not exceed cell capacity.Thus a collector and cell arrangement having an uneven flux deliversless total flux than one with a more consistent flux density.

An example of a solar conversion system 40A is shown schematically inFIG. 12 having a non-parabolic collector 42, a receiver 48B, and aresistive load 72 in electrical communication with the receiver 48B. Thereceiver module 48B is schematically represented as part of a circuit 70having a current source with current i_(L) in parallel with a diodehaving current i_(D). The circuit 70 is coupled to the receiver module48B by conductive members 74 to the resistive load 72. Resistive load 72may be any device that operates on or otherwise runs on or draws anelectrical current or voltage, as well as any device or system for thestorage of electrical current power or voltage. In an example ofoperation, sun rays 44 reaching the collector 42 reflect from thecollector 42 to form reflected rays 46. As discussed above, theconfiguration of the collector 42 focuses the reflected rays 46 within aplane 53 (FIG. 4B) that strikes the conversion cell 54 (FIG. 8). Theconversion cell 54 converts the solar energy of the focused rays 46 toelectricity that is communicated to the resistive load 72 through theconductive members 74.

FIG. 13 is a side perspective views of an example of a collector 42mounted on a frame 76. Aluminum 5052 is an example material suitable forthe frame 76. FIGS. 13A and 13B provide upper and lower plan views ofthe collector 42 and frame 76 of FIG. 13. The collector 42 rests onelongate cradles 77 shown substantially parallel to axis A_(W) eachproximate to opposing sides of the collector 42. The cradles 77 have aside contoured to receive the convex side of collector 42. The cradles77 are supported and oriented by vertically oriented legs 78 that attachto a side of the cradles 77 opposite the side receiving the collector42. The legs 78 are shown attached at an end and at about a mid portionof each cradle 77. The position of the legs 78 and their relativeheights determine the angle at which the cradle 77 is oriented withrespect to horizontal, and thus the orientation of the collector 42. Theends of the legs 78 opposite the cradle 77 are attached to elongatedgirders 80 that are shown parallel to the cradles 77. A channel member84 having a C-shaped length-wise cross section is provided in the spacebetween the parallel girders 80. The channel member 84 is oriented sothe open portion of the “C” is facing downward away from the collector42. An optional lip 82 is shown formed on the elongate sides of thecollector 42 at its outer periphery. The lip 82 as shown is parallel toa line spanning between the X and Z axes. The lip 82 can retain thecollector 42 in its profiled shape.

FIG. 14A illustrates a front elevation view of the collector 42 of FIG.13 taken along the X axis. The front portion of the collector 42 sitslower than its rear so that the collector 42 slopes upward from thefront to rear portion. The lip 82 is shown projecting upward from thelateral sides of the collector 42 from the front to rear portion. FIG.14B is a rear view of the collector 42 of FIG. 13 illustrating thecontoured cradles 77 supporting and orienting the collector 42. Althoughshown disposed proximate to the lateral edges of the collector 42, thecradles 77 could be disposed closer together and inward from the edges,or replaced by a single wider cradle (not shown). Lateral side views ofthe collector 42 are illustrated in FIGS. 15A and 15B. The collector 42as shown is oriented to focus an image of reflected sun rays onto aforward disposed receiver (not shown). As discussed above, along itslength the collector 42 is non-parabolic and asymmetric.

A portion of an example of a collector array 83 is depicted in a sideperspective view in FIG. 16. The array 83 illustrated includes fourcollectors 42, 45, two of which are adjacently located in a row withtheir concave sides facing in the same direction. The other twocollectors 42, 45 are in an adjacent row with their respective concavesides facing in a direction opposite that of the first row. Alternativeembodiments of an array 83 exist having any number of collectors. Theframe 76 that supports the collectors 42, 45 straddles the C-channelmember 84. The frame 76 of adjacent rows may be connected to one anotheror their C-channel members 84 mounted onto a platform (not shown) sothat the entire array 83 can be simultaneously and continuously orientedinto maximum sunlight exposure.

An alternate example of a receiver assembly 50A is shown having aconversion cell 54A set onto a surface of a planar base 49A. In oneexample, the base 49A draws thermal energy from the conversion cell 54Athereby acting as a heat sink. A housing 88 perpendicularly projectsfrom the base 49A periphery and covers the side of the base 49A wherethe cell 54A is located. An aperture is formed through the housing 88providing an unobstructed path for the reflected rays to impinge uponthe conversion cell 54A. Tubular heat pipes 86 are shown routed througha lower lateral side of the housing 88 and into channels 89 formedlengthwise in the base 49A. The heat pipes 86 can be made from aluminumand have about a 0.3 inch diameter. After exiting the base 49A, the heatpipes 86 project in opposite directions at about a 90° angle. Fins (notshown) may be provided on the heat pipes 86 for increasing heatdissipation to ambient. The pipes 86 can contain a thermal fluid thatvaporizes from heat drawn from the cell 54A, then the vaporized fluiddescends to the lower end of the assembly. Heat is transferred from thevaporized fluid to ambient through the wall of the pipes 86 and fins tocondense the fluid. The center of the heat pipe 86 can include a wickingmedium for drawing the condensed fluid upward and adjacent the cell 54Afor another cycle of cooling. A heat pipe 86 suitable for use asdescribed herein can be obtained from Thermacore Inc., 780 Eden Rd.,Lancaster, Pa. 17601, Ph (717)569-6551 or Aavid Thermalloy, 70Commercial St., Concord, N.H. 03301 USA, Tel: (603) 224-9988, Fax: (603)223-1790. The receiver assembly 50A is attachable to the collectors 42,45 via corresponding bolt holes 90, 91 respectively formed in the base49A and the collectors 42, 45. Optionally, the receiver 48 may beattached without bolts, such as with an adhesive or welding or can besuspended from the rear side of a collector 42 using a continuation ofthe cradle 77. Moreover, maximizing the contact area between the base49A and the collector 42, 45 increases heat transfer between the base49A and the collector 42, 45 thus increasing heat transfer from theconversion cell 54A. In an alternative embodiment, waste heat from thepipes 86 and/or fins can be captured for use in water heating. Thiswould derive economic benefit from a much higher proportion of thecollected solar energy.

Example

In one non-limiting example of the device disclosed herein, thecollector 42 concentrates 650 suns on a solar cell having a 1 cm² area.The collector 42 is a rectangular shaped stamped aluminum piece(approximately 14″ by 8″) constituting a non-parabolic solid. The solidis coated with a reflective coating with reflectivity of approximately95%. This piece is designed to create a square beam which converges on afocal plane 1 cm² some inches to the side of the collector 42. Thedesign of the collector 42 creates an even energy flux across the entirespan of the focal plane without the interposition of any correctiveoptics (e.g., a homogenizer or diffuser). An optical lens may be placedin front of the focal plane to protect the cell from weather. A typicalmounting configuration would place eight rectangles, one above theother, with another eight high array set by its side at 180°orientation. A multijunction cell mounts on a bracket at the focal planeof the collector 42. The focal plane is shaded by the forward positionedcollector 45. The collector 42 at the front of a row is equipped with abracket for holding the cell. The collector 42 and associated cell 54can generate approximately 180-200 W. Each collector 42 and cell 54 isinstalled at an angle such that a tracking system keeps all reflectivesurfaces in full sunlight at all times, while all the cells and heatsinks will be in full shade. Each cell 54 can generate about 22.5 wattsof direct electrical current at an efficiency of about 35%. Each cell 54is attached to a heat sink which collects and distributes the waste heatfrom that cell (approximately 40 watts).

In an alternative embodiment, each cell has electrical connections whichcarry the produced electricity first to collection points, and then toan inverter (not shown), which converts the direct current toalternating current. The inverter, which can be an off the shelf item,can be connected to an associated electrical grid and returned to apower provider for compensation. Energy storage, such as batteries, canbe inserted between the cell 54 and a centralized inverter system, thissystem can become a stand-alone alternative to the conventionalelectrical grid for those without access to a grid or prefer to beindependent of a grid. The battery size is determined by the size of thesystem, the climate of the installation and the duration of storagecapacity desired.

Concentrating the solar energy reduces the material needed in the solarcell 54 per 2.88 kW from about 2000 in² (typically used in conventionalphotovoltaic cells) to about 20 in². The reduced size can significantlyreduce cost of the present system since solar cells are usually the mostexpensive component in a solar energy system. Moreover, concentratedphotovoltaic cells (CPV) use less silicon than traditional photovoltaics(PV), which enhances power output since the power output of silicondecreases by about 1% per 4° F. A less silicon-intensive system, i.e.CPV, will perform far better than a PV system at high ambienttemperatures, such as hot summer afternoons when solar production shouldbe greatest. Unlike solar thermal systems, the system described hereindoes not require water to cool.

The present invention described herein, therefore, is well adapted tocarry out the objects and attain the ends and advantages mentioned, aswell as others inherent therein. While a presently preferred embodimentof the invention has been given for purposes of disclosure, numerouschanges exist in the details of procedures for accomplishing the desiredresults. These and other similar modifications will readily suggestthemselves to those skilled in the art, and are intended to beencompassed within the spirit of the present invention disclosed hereinand the scope of the appended claims. While the invention has been shownin only one of its forms, it should be apparent to those skilled in theart that it is not so limited but is susceptible to various changeswithout departing from the scope of the invention.

1. A solar energy conversion system to convert solar light energy intoelectrical energy, the system comprising: a. a first solar collectorhaving a reflective front surface contoured so that when positioned toreceive solar light energy from the sun, the solar light energy contactsthe reflective surface, is reflected from the collector outwardly fromthe reflective surface, and is concentrated in a planar portion of aplane having substantially constant flux density throughout the planarportion to thereby define a planar focal area; b. a photovoltaic cellhaving at least a portion of a surface coincident with the planar focalarea to receive the concentrated light energy thereon; and c. aresistive load in electrical communication with the photovoltaic cell sothat the concentrated light energy received by the photovoltaic cell isthereby converted to electrical energy and communicated to the resistiveload.
 2. A system as defined in claim 1, wherein the planar focal areahas a shape of the outer peripheries thereof being selected from thelist consisting of: a rectangle, a square, a circle, and an ellipse. 3.A system as defined in claim 1, wherein a ratio of photovoltaic cellsurface area to the planar focal area ranges from about 1:2 to about3:2.
 4. A system as defined in claim 1, wherein discrete amounts ofsolar light energy reflect from locations on the reflective surfacedefine paths from the reflective surface to corresponding locations onthe focal area and wherein the paths do not intersect.
 5. A system asdefined in claim 1, further comprising a second solar collector having afront surface and a rear surface positioned to face the reflective frontsurface of the first solar collector, a shaded area adjacent the secondsolar collector rear surface, and wherein the photovoltaic cell isconnected to the rear surface of the second solar collector andpositioned within the shaded area to receive solar light energy whenreflected from the reflective front surface of the first solarcollector.
 6. A system as defined in claim 1, further comprising a heattransfer system in thermal communication with the photovoltaic cell. 7.A system as defined in claim 1, further comprising a multiplicity ofadditional collectors and corresponding photovoltaic cells, wherein thecollectors are arranged in rows to form an array of collectors.
 8. Asystem for converting solar energy into electricity comprising: a firstsolar collector having a reflective surface that is shaped so that whensolar energy contacts the reflective surface, the solar energy isreflected away from the reflective surface and converges into a planararea to define a focal area of concentrated light having a substantiallyuniform flux density; a second solar collector disposed on the side ofthe first solar collecting having the reflective surface and angled withrespect to horizontal so that when solar energy is directed towards thesecond solar collector at least a portion of the solar energy isshielded by the second solar collector to form a shaded space; a solarcell having a reactive surface disposed coincident with the focal areaand mounted on a side of the second solar collector in the shaded space,so that when the concentrated light of the focal area impinges on thereactive surface electricity is generated in the solar cell; a heat sinkin thermal communication with the solar cell; and a resistive load inelectrical communication with the solar cell, so that when electricityis generated in the solar cell, it is communicated to the resistiveload.
 9. A system as defined in claim 8, wherein the size of the focalarea ranges from about 55% to about 70% of the size of the solar cellsurface.
 10. A system as defined in claim 8, further comprising a heatpipe heat transfer circuit in thermal communication with the heat sink.